Question

Tìm x:

a) \(\dfrac{2}{5}+\dfrac{3}{5}.x+-\dfrac{1}{4}\)

b) \(\dfrac{7}{9}-\dfrac{2}{9}.x=\dfrac{4}{3}\)

c) \(\left(\dfrac{3}{10}-x\right).\dfrac{-1}{3}=\dfrac{-2}{5}\)

d) \(\dfrac{1}{3}+\dfrac{1}{3}:x=-7\)

Answer 1

câu a ko tính đc x

\(b,\dfrac{2}{9}.x=\dfrac{7}{9}-\dfrac{4}{3}=\dfrac{7}{9}-\dfrac{12}{9}=\dfrac{-5}{9}\)

\(x=\dfrac{-5}{9}:\dfrac{2}{9}\)

\(x=\dfrac{-6}{9}.\dfrac{9}{2}=\dfrac{-54}{18}=-3\)

 

\(c,\dfrac{3}{10}-x=\dfrac{-2}{5}:\dfrac{-1}{3}=\dfrac{-2}{5}.\dfrac{3}{-1}=\dfrac{-6}{-5}=\dfrac{6}{5}\)

\(x=\dfrac{3}{10}-\dfrac{6}{5}=\dfrac{3}{10}-\dfrac{12}{10}=\dfrac{-9}{10}\)

 

\(d,\dfrac{1}{3}:x=\left(-7\right)-\dfrac{1}{3}=\dfrac{-21}{3}-\dfrac{1}{3}=\dfrac{-22}{3}\)

\(x=\dfrac{1}{3}:\dfrac{-22}{3}=\dfrac{1}{3}.\dfrac{3}{-22}=\dfrac{3}{-66}=\dfrac{-1}{22}\)